[Patent document 1] JP 2006-284459 A
There is conventionally known a liquid level detection apparatus which detects a level of a liquid. In this apparatus, an arm member connects (i) a rotation member whose axis is axially supported by a fixed member fixed to a tank and (ii) a float which floats on the liquid in the tank and moves up-and-down to follow the level of the liquid; such an up-and-down movement is converted into a rotational movement of the rotation member, thereby enabling the detection of the level of the liquid.
Patent document 1 describes one example of such a liquid level detection apparatus in which a magnet, which is fixed to a rotation member, rotates according to an up-and-down movement of a float, thereby generating a magnetic field; the generated magnetic field is detected by a magnetoelectric transducer held at a fixed member. The magnetoelectric transducer thereby outputs an electrical signal indicating the level of the liquid. That is, the apparatus disclosed in Patent document 1 achieves a conversion from the rotational movement to the electrical signal in a non-contact manner between the rotation element and the electrical conversion element: thus, a high durability is obtained. Further, in the apparatus of Patent document 1, the magnet is embedded into the rotation member, thereby stabilizing a holding position of the magnet; the level of the liquid is thus detected based on the detection result of the magnetic field generated by the magnet. This improves the detection accuracy.
In the apparatus of Patent document 1, the magnet is embedded in a rotation member using an insert molding which needs a complicated molding operation; thereby, the productivity may not be improved.